1. Field of the Invention
The present invention relates to a weak-magnetic field sensor using printed circuit board manufacturing technique and a method of manufacturing the same, and more particularly to a weak-magnetic field sensor using printed circuit board manufacturing technique and a method of manufacturing the same which is adapted to be mounted on a mobile communication terminal to detect earth magnetism to obtain positional information.
2. Description of the Prior Art
In recent trend of offering various additional information services mobile involved in propagation of mobile phones and mobile terminals, a positional information service becomes established as an essential service, and more detailed and convenient services are required hereafter.
To achieve positional information, it is necessary to provide a sensor capable of precisely finding out a current position. As such means for providing positional information, a weak-magnetic field sensor which is intended to detect magnetism of earth to obtain positional information has been used. As a component commonly used in such a weak-magnetic field sensor, there is a flux gate sensor.
The flux gate sensor uses highly permeable magnetic strips for its core components. The flux gate sensor is comprised of a primary coil wound around one of the two magnetic cores and a secondary coil wound around the other of the magnetic cores, and is capable of recognizing a current position by detecting difference between voltage generated from the primary coil and voltage generated from the secondary coil due to variations of magnetic fields of the cores.
Such a conventional flux gate sensor is manufactured in such a way that two cylindrical core made of highly permeable magnetic material are wound with copper wires in a certain direction. More specifically, a copper wire as a driving coil (a primary coil) is wound around a magnetic core in a certain direction while maintaining constant spacing and pressure. Subsequently, a pickup coil (a secondary coil) is wound around the magnetic core to detect magnetic field generated from the magnetic core due to the driving coil. As is the case with the winding of the driving coil, a copper wire as the pickup coil is wound at a constant spacing under constant pressure.
As such, such a flux gate, which is fabricated by winding copper wires, is comprised of a driving coil and a pickup coil for detecting magnetic field generated from the driving coil. The copper coils are wound around the magnetic cores utilizing a wire coil technology well known in the art. At this point, the secondary coil must be wound to be directed in a X-axis direction and a Y-axis direction so as to precisely make an analysis of sensitivity of magnetic field. However, although a conventional flux gate sensor must maintain-positional accuracy of a wound coil, it is difficult to maintain the positional accuracy. Since the positional accuracy is easily affected by temperature, light or surface material due to such configuration, accuracy of its attributes is deteriorated.
In addition, since the flux gate sensor is fabricated such that a coil is directly wound around a magnetic core, it has a disadvantage in that the coil is frequently cut. Moreover, since the sensor itself becomes large, it is not suitable to miniaturization and weight saving of electric appliances. The enlargement of the sensor requires increase of electricity consumption, so that the sensor cannot meet miniaturization and reduction of electricity consumption of electric appliances.
To overcome disadvantages of such a conventional flux gate sensor, a weak-magnetic field sensor is proposed in U.S. Pat. Nos. 5,936,403 and 6,270,686, which is manufactured in such a way that amorphous boards having circular etched portions are stacked on both upper and lower surfaces of a glass epoxy base having specific conductive patterns to form an amorphous flat board core, and glass epoxy bases etched to form X coils and Y coils are stacked on the amorphous flat board core. However, since the flux gate sensor disclosed in U.S. Pat. No. 5,936,403 requires a process of preparing the amorphous flat board core by carrying out an etching treatment into a circular shape and stacking of amorphous boards while conforming to the circular etched portion, its manufacturing process is complicated and high manufacturing cost is required due to stacking of many amorphous boards.
Accordingly, the inventor has been studied to solve the above-mentioned problems. As a result, the inventor developed a novel weak-magnetic field sensor using printed circuit board manufacturing technique and a method of manufacturing the same, which meets the needs for miniaturization and reduction of electric power consumption.
The present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a weak-magnetic field sensor using printed circuit board manufacturing technique and a method of manufacturing the same which can detect weak-magnetic field with precision and maintain positional accuracy.
Another object of the present invention is to provide a weak-magnetic field sensor using printed circuit board manufacturing technique and a method of manufacturing the same which is capable of meeting the need for high density mounting required in a field of application such as mobile phones by accomplishing miniaturization, excellent magnetic efficiency and low electric power consumption by an etching technique for a printed circuit board.
In order to accomplish the above object, the present invention provides a weak-magnetic field sensor comprising: a magnetic layer which is patterned in a certain shape; a first stacked board which is stacked on a lower surface of the magnetic layer and which is formed with a first driving pattern; a second stacked board which is stacked on an upper surface of the magnetic layer and which is formed with a second driving pattern, the first and second driving patterns being electrically connected to each other; a third lower stacked board which is stacked on a lower surface of the first stacked board and which is formed with a first pickup pattern; and a third upper stacked board which is stacked on an upper surface of the second stacked board and which is formed with a second pickup pattern, the third lower and upper stacked boards being electrically connected to each other.
Furthermore, the present invention provides A method of manufacturing a weak-magnetic field sensor using printed circuit board manufacturing technique, comprising the steps of: preparing a first stacked board by stacking a first conductive layer, a first base layer and a magnetic layer in this order; preparing a second stacked board by stacking a second base layer and a second conductive layer on the first stacked board in this order; forming via-holes at the first and second conductive layers to electrically connect both the conductive layers to each other; providing driving patterns corresponding to the magnetic layer to the first and second conductive layers; preparing a pair of third stacked boards by stacking a third base layer and a third conductive layer on a lower surface of the first stacked board and by stacking a third base layer and a third conductive layer on an upper surface of the second stacked board; forming through holes at the pair of third conductive layers to electrically connect the pair of third conductive layers to each other; and providing pickup patterns to the pair of conductive layers.